Step one: make sure you use Clipping on each of your new layers!
Step two: make a dark shadow using normal pen and the smudge brush
Step three: do it again higher up with the same brushes as step two
Step four: using the same brushes draw a U shape where the highlight is
Step five: select a lighter color and use the fragment brush set to 35% opacity
Step six: use pencil brush to make light splashes across the eye and smudge the half closer to the light source
Step seven: use pencil brush to make more detailed light splashes
Step eight: set new layer to dodge and use your original base color with water color soft set to 31% opacity
Step nine: using the original pens from step one get a light color of your choice to make highlights
Step ten: use pencil brush to draw out some details and the water color soft to fade it to your liking
Step eleven: repeat step nine with a new color
Step twelve: set new layer to add with base color using pencil and smudge, and then white and normal pen